There are two principal ways for a user to configure a home telephone system to provide a messaging service to an incoming caller. A first way is to have a telephone answering device, also known as an “answering machine” integrated into or coupled to a telephone at the user's home. Such a device will typically enter an off-hook or answered state after a predetermined number of unanswered rings associated with an incoming call, and then play an outgoing message (OGM) to an incoming caller, after which the incoming caller is offered the opportunity to record an incoming message. The answering machine has a drawback in that it cannot record a message if the telephone line is busy, i.e., the user is engaged in a previous call.
A second way is for the user to purchase a service from a telephone service provider wherein the telephone service provider will store incoming messages at a central location, and play the incoming messages to the user upon request. This second option is advantageous in that the OGM and recording activities occur between the central location and the incoming caller, and thus allow for the issuance of the OGM and recording of the incoming message, even if the target telephone is busy because the user is engaged in a previous telephone call.
A disadvantage of a user procuring messaging services from a service provider is that an incoming message may be waiting for the user and the user may not be aware of the stored incoming message. This can be contrasted with the traditional answering machine option, wherein the answering machine typically illuminates an LED or seven-segment display to inform the user of the existence of or number of stored messages. To overcome this drawback, a feature known as Voicemail Message Waiting Indicator (VMWI) was developed, wherein the service provider sends a signal to the user's telephone to cause it to illuminate an LED indicative of one or more waiting voicemail messages. This feature is described, for example, in BellCore Standard TR-NWT-001401, “Visual Message Waiting Indicator, Generic Requirements, FSD-01-02-2000, incorporated herein by reference.
A drawback of the traditional VMWI service is that it provides for the issuance of the VMWI signal only if the user's telephone is in an on-hook condition, i.e., is not engaged in a telephone call. If the user's telephone is off-hook, the traditional VMWI service waits until the telephone transitions to the on-hook state, and then provides the VWMI signal. Thus, if a user is engaged in a telephone call, the user will not be made aware of a new incoming message until after the telephone call is completed. This drawback may be of even greater magnitude if the telephone call is lengthy, because the standard allows for the VMWI signal to be dropped completely, i.e., not delivered, if there is a wait of more than 2.5 hours.
There is therefore a need for a VMWI service and apparatus that provides a VMWI signal even if a user's telephone is off-hook. There is also a need for a telephone adapted to receive a VMWI signal when off-hook, and to provide an indication of the receipt of the VMWI signal, such as the illumination of an LED, or the display of caller ID data associated with the message leaving party.